docs: def is_causal_central(graph: BELGraph, node: BaseEntity) -> bool:
      """Return true if the node is neither a causal sink nor a causal source.
  
      - Does have causal in edges(s)
      - Does have causal out edge(s)
      """
      return has_causal_in_edges(graph, node) and has_causal_out_edges(graph, node)